ListView布局之View复用原理举例
1.简单介绍：
ListView是android开发中经常使用的控件，系统自带的那些样式，我就不列举了。
今天主要看一下。一个模仿系统历史通话记录的ListView。
效果例如以下：
上面ListView的样式还能够更复杂。首先看一下这个简单的ListView的Item的布局文件：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/contacts_items"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ffffff"
android:orientation="vertical" >
<View
android:id="@+id/topLine"
android:layout_width="fill_parent"
android:layout_height="1dp"
android:background="#ff474745" />
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="60dp"
android:gravity="center_vertical"
android:paddingRight="1.0dip" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:gravity="center_vertical"
android:orientation="horizontal" >
<ImageView
android:id="@+id/imgHead"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_marginLeft="15dp"
android:layout_marginRight="10dp"
android:contentDescription="" />
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:gravity="center_vertical"
android:orientation="vertical" >
<TextView
android:id="@+id/tvName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:ellipsize="end"
android:singleLine="true"
android:textSize="14.0sp" />
<TextView
android:id="@+id/tvTelephone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginTop="4.0dip"
android:ellipsize="end"
android:singleLine="true"
android:textColor="#ffcccccc"
android:textSize="12sp" />
<TextView
android:id="@+id/tvDate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="0.2dip"
android:layout_marginTop="0dip"
android:ellipsize="end"
android:singleLine="true"
android:textColor="#ffcccccc"
android:textSize="12sp" />
</LinearLayout>
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentRight="true"
android:layout_centerVertical="true"
android:gravity="center_vertical"
android:orientation="horizontal" >
<Button
android:id="@+id/btnCall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginRight="0.2dip"
android:layout_marginTop="0dip"
android:ellipsize="end"
android:singleLine="true"
android:textColor="#ff0000ff"
android:focusable="false"
android:textSize="12sp" />
</LinearLayout>
</RelativeLayout>
<View
android:id="@+id/bottomLine"
android:layout_width="fill_parent"
android:layout_height="1dp"
android:background="#ff1c1c1b" />
<View
android:id="@+id/lastLine"
android:layout_width="fill_parent"
android:layout_height="1dp"
android:background="#ff474745"
android:visibility="gone" />
</LinearLayout>没什么问题吧？可是你一定要注意Button的一个属性：android:focusable="false"，假设不加这个属性，会使得ListView的OnItemClick被屏蔽。
因为是模仿通话记录，那么Item里面的这个属性。我们还是封装到一个类里面吧。
/*
* $filename: Model.java,v $
* $Date: 2014-4-27 $
* Copyright (C) ZhengHaibo, Inc. All rights reserved.
* This software is Made by Zhenghaibo.
*/
package com.example.testaa;
import org.androidannotations.annotations.EBean;
/*
*@author: ZhengHaibo
*web: http://blog.csdn.net/nuptboyzhb
*mail: zhb931706659@126.com
*2014-4-27 Nanjing,njupt,China
*/
@EBean
public class Model {
private int imgHead;//头像资源ID
private String name;//姓名
private String telephone;//电话号码
private String date;//日期
public int getImgHead() {
return imgHead;
}
public void setImgHead(int imgHead) {
this.imgHead = imgHead;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getTelephone() {
return telephone;
}
public void setTelephone(String telephone) {
this.telephone = telephone;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
}
接下来。思路非常清晰。就是继承BaseAdapter类，重写它的几个重要方法：
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return 0;
}依照我们的需求，我们必须在getView类中，为Item布局中的每个View进行关联。设置对应的參数。而对于Button，还要设置对应的事件监听器。我们必须注意的是：在设置事件监听器的时候。我们必须将当前的Item的位置信息position传递给监听器。否则的话，onClick方法无法知道当前按下的是哪个button。因此，我们写了一个内部类，实现OnClickListener接口，这个类的须要有一个属性来保存Item的位置。
因此，我们的BaseAdapter1代码例如以下：
/*
* $filename: BaseAdapter1.java,v $
* $Date: 2014-4-27 $
* Copyright (C) ZhengHaibo, Inc. All rights reserved.
* This software is Made by Zhenghaibo.
*/
package com.example.testaa;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
/*
*@author: ZhengHaibo
*web: http://blog.csdn.net/nuptboyzhb
*mail: zhb931706659@126.com
*2014-4-27 Nanjing,njupt,China
*/
public class BaseAdapter1 extends BaseAdapter {
private Context context;
private List<Model> listViewData;
private int layoutResId;//ListView每个Item的布局文件
public BaseAdapter1(Context context,int layoutResId) {
this.context = context;
this.layoutResId = layoutResId;
listViewData = new ArrayList<Model>();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
convertView = LayoutInflater.from(context).inflate(layoutResId,null);
Model model = listViewData.get(position);
ImageView imageView = (ImageView)convertView.findViewById(R.id.imgHead);
imageView.setImageBitmap(BitmapFactory.decodeResource(context.getResources(), model.getImgHead()));
TextView tvName = (TextView)convertView.findViewById(R.id.tvName);
tvName.setText(model.getName());
TextView tvTelephone = (TextView)convertView.findViewById(R.id.tvTelephone);
tvTelephone.setText(model.getTelephone());
TextView tvDate = (TextView)convertView.findViewById(R.id.tvDate);
tvDate.setText(model.getDate());
Button btnCall = (Button) convertView.findViewById(R.id.btnCall);
btnCall.setText("拨打电话");
btnCall.setOnClickListener(new ListViewButtonOnClickListener(position) );
return convertView;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return listViewData.get(position);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
if(null == listViewData){
return 0;
}
return listViewData.size();
}
/**
* 加入一条记录
* @param model
*/
public void addModel(Model model){
listViewData.add(model);
}
/**
* 获取一条记录
* @param i
* @return
*/
public Model getModel(int i){
if(i<0||i>listViewData.size()-1){
return null;
}
return listViewData.get(i);
}
/**
* 清除全部数据
*/
public void clear(){
listViewData.clear();
}
class ListViewButtonOnClickListener implements OnClickListener{
private int position;//记录ListView中Button所在的Item的位置
public ListViewButtonOnClickListener(int position) {
this.position = position;
}
@Override
public void onClick(View v) {
Toast.makeText(context,listViewData.get(position).getTelephone(), Toast.LENGTH_SHORT).show();
}
}
}
由此可见，假设我们须要定制Item的布局，我们仅仅须要改动的地方除了Item的布局文件以外，还要将Adapter里的getView方法进行对应的改动。
接下来看一下Activity的測试代码
package com.example.testaa;
import java.text.SimpleDateFormat;
import java.util.Date;
import org.androidannotations.annotations.AfterViews;
import org.androidannotations.annotations.EActivity;
import org.androidannotations.annotations.ViewById;
import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.Toast;
@EActivity(R.layout.activity_list_1)
public class ActivityList1 extends Activity implements OnItemClickListener{
@ViewById
ListView listView;
//ListView的设配器
private BaseAdapter1 baseAdapter1;
@AfterViews
void afterViewInitList(){
baseAdapter1 = new BaseAdapter1(this,R.layout.listview1);
listView.setAdapter(baseAdapter1);
listView.setOnItemClickListener(this);
for(int i=0;i<10;i++){
Model model = new Model();
model.setImgHead(R.drawable.ic_launcher);
model.setName("Name"+i);
model.setTelephone("手机 1311111111"+i);
model.setDate(new SimpleDateFormat().format(new Date()).toString());
baseAdapter1.addModel(model);
}
baseAdapter1.notifyDataSetChanged();
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) {
// TODO Auto-generated method stub
Log.d("ItemClick", "pos="+position);
String string = "clicked item"+position+"content="+baseAdapter1.getModel(position).getTelephone();
Toast.makeText(this, string, Toast.LENGTH_SHORT).show();
}
}
此时。就完毕了我们想要的功能。
Item的点击事件和Button的点击事件互不冲突。
问题二：
向微信，QQ，易信等聊天界面的ListView则有所不同。
我们上述的样例是：Item仅仅有一个布局。而聊天界面其中ListView的Item布局有多种，比方显示文字的布局，显示图片的布局，显示语音的布局等等。除此之外。我们还要依据消息的发送者，将其左右分开。在这里，仅仅演示左右的文本。原理都是都是一样的。
先看一下布局文件
左右文本的布局文件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<ImageView
android:id="@+id/imgHead"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_margin="5dip"
android:src="@drawable/ic_launcher"
/>
<Button
android:id="@+id/btn_left_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/imgHead"
android:layout_marginTop="5dip"
android:layout_marginBottom="5dip"
android:textColor="#404040"
android:textSize="16sp"
android:gravity="center"
android:focusable="false"
android:background="@drawable/chatfrom_bg_normal"
/>
</RelativeLayout>右边的布局文件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<ImageView
android:id="@+id/imgHead"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_margin="5dip"
android:src="@drawable/ic_launcher"
/>
<Button
android:id="@+id/btn_right_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toLeftOf="@+id/imgHead"
android:layout_marginTop="5dip"
android:layout_marginBottom="5dip"
android:textColor="#404040"
android:textSize="16sp"
android:gravity="center"
android:focusable="false"
android:background="@drawable/chatto_bg_normal"
/>
</RelativeLayout>再看一下适配器，基本和上一个样例一样，不一样无非就是getView方法的差异。
/*
* $filename: BaseAdapter1.java,v $
* $Date: 2014-4-27 $
* Copyright (C) ZhengHaibo, Inc. All rights reserved.
* This software is Made by Zhenghaibo.
*/
package com.example.testaa;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
/*
*@author: ZhengHaibo
*web: http://blog.csdn.net/nuptboyzhb
*mail: zhb931706659@126.com
*2014-4-27 Nanjing,njupt,China
*/
public class ChatBaseAdapter extends BaseAdapter {
private Context context;
private List<Msg> listViewData;
public ChatBaseAdapter(Context context) {
this.context = context;
listViewData = new ArrayList<Msg>();
}
/**
* 依据发送消息的类型进行分类，不同的消息类型不同的布局
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
Msg msg = listViewData.get(position);
if(msg.isSelf()){//自己发送的消息
convertView = LayoutInflater.from(context).inflate(R.layout.list_item_right_text,null);
ImageView imgHead =(ImageView) convertView.findViewById(R.id.imgHead);
imgHead.setImageBitmap(BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher));
Button btn = (Button)convertView.findViewById(R.id.btn_right_text);
btn.setText(msg.getContent());
btn.setOnClickListener(new ListViewButtonOnClickListener(position));
}else {//对方发送的消息
convertView = LayoutInflater.from(context).inflate(R.layout.list_item_left_text,null);
ImageView imgHead =(ImageView) convertView.findViewById(R.id.imgHead);
imgHead.setImageBitmap(BitmapFactory.decodeResource(context.getResources(), R.drawable.ic_launcher));
Button btn = (Button)convertView.findViewById(R.id.btn_left_text);
btn.setText(msg.getContent());
btn.setOnClickListener(new ListViewButtonOnClickListener(position));
}
return convertView;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return listViewData.get(position);
}
@Override
public int getCount() {
// TODO Auto-generated method stub
if(null == listViewData){
return 0;
}
return listViewData.size();
}
/**
* 加入一条记录
* @param Msg
*/
public void addMsg(Msg Msg){
listViewData.add(Msg);
}
/**
* 获取一条记录
* @param i
* @return
*/
public Msg getMsg(int i){
if(i<0||i>listViewData.size()-1){
return null;
}
return listViewData.get(i);
}
/**
* 清除全部数据
*/
public void clear(){
listViewData.clear();
}
class ListViewButtonOnClickListener implements OnClickListener{
private int position;//记录ListView中Button所在的Item的位置
public ListViewButtonOnClickListener(int position) {
this.position = position;
}
@Override
public void onClick(View v) {
Toast.makeText(context,listViewData.get(position).getContent(), Toast.LENGTH_SHORT).show();
}
}
}
Activity的代码为：
package com.example.testaa;
import org.androidannotations.annotations.AfterViews;
import org.androidannotations.annotations.EActivity;
import org.androidannotations.annotations.ViewById;
import android.app.Activity;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.Toast;
@EActivity(R.layout.activity_list_2)
public class ActivityList2 extends Activity implements OnItemClickListener{
@ViewById
ListView listView;
private ChatBaseAdapter chatBaseAdapter;
@AfterViews
void afterViewInitList(){
chatBaseAdapter = new ChatBaseAdapter(this);
listView.setAdapter(chatBaseAdapter);
listView.setOnItemClickListener(this);
for(int i=0;i<10;i++){
Msg msg = new Msg();
if(i%2==0){
msg.setSelf(false);
}else {
msg.setSelf(true);
}
msg.setContent("abc"+i);
chatBaseAdapter.addMsg(msg);
}
chatBaseAdapter.notifyDataSetChanged();
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int position, long arg3) {
// TODO Auto-generated method stub
Log.d("ItemClick", "pos="+position);
String string = "clicked item"+position+"content="+chatBaseAdapter.getMsg(position).getContent();
Toast.makeText(this, string, Toast.LENGTH_SHORT).show();
}
}
效果：
关于聊天界面的很多其它内容可參考博文：http://blog.csdn.net/xyz_lmn/article/details/13745489
原理基本一样。
注意：整个项目的代码使用的是AndroidAnnotation框架，本博客的代码下载：http://download.csdn.net/detail/nuptboyzhb/7260915
